Increase default file handle limits for daemons

Linux still defaults to a 1024 open file handle limit. This causes
scalability problems for libvirtd / virtlockd / virtlogd on large
hosts which might want > 1024 guest to be running. In fact if each
guest needs > 1 FD, we can't even get to 500 guests. This is not
good enough when we see machines with 100's of physical cores and
TBs of RAM.

In comparison to other memory requirements of libvirtd & related
daemons, the resource usage associated with open file handles
is essentially line noise. It is thus reasonable to increase the
limits unconditionally for all installs.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
This commit is contained in:
Daniel P. Berrange 2017-03-15 16:51:51 +00:00
parent b2aca2db7e
commit 27cd763500
3 changed files with 14 additions and 2 deletions

View File

@ -24,8 +24,11 @@ ExecStart=@sbindir@/libvirtd $LIBVIRTD_ARGS
ExecReload=/bin/kill -HUP $MAINPID
KillMode=process
Restart=on-failure
# Override the maximum number of opened files
#LimitNOFILE=2048
# At least 1 FD per guest, often 2 (eg qemu monitor + qemu agent).
# eg if we want to support 4096 guests, we'll typically need 8192 FDs
# If changing this, also consider virtlogd.service & virtlockd.service
# limits which are also related to number of guests
LimitNOFILE=8192
[Install]
WantedBy=multi-user.target

View File

@ -13,6 +13,10 @@ ExecReload=/bin/kill -USR1 $MAINPID
# cause the machine to be fenced (rebooted), so make
# sure we discourage OOM killer
OOMScoreAdjust=-900
# Needs to allow for max guests * average disks per guest
# libvirtd.service written to expect 4096 guests, so if we
# allow for 4 disks per guest, we get:
LimitNOFILE=16384
[Install]
Also=virtlockd.socket

View File

@ -13,6 +13,11 @@ ExecReload=/bin/kill -USR1 $MAINPID
# cause the machine to be fenced (rebooted), so make
# sure we discourage OOM killer
OOMScoreAdjust=-900
# Need to have at least one file open per guest (eg QEMU
# stdio log), but might be more (eg serial console logs)
# libvirtd.service written to expect 4096 guests, so if we
# guess at 2 log files per guest here (stdio + 1 serial):
LimitNOFILE=8192
[Install]
Also=virtlogd.socket